Field of the Invention
The present invention relates to a magnetic carrier that is used in a two-component developer for developing (visualizing) an electrostatic latent image (electrostatically charged image) in accordance with an electrophotographic method, and relates to a two-component developer that has the magnetic carrier.
Description of the Related Art
Electrophotographic methods, which in recent years have come to be widely used in copiers, printers and the like, are required to cope with various targets such as fine lines, small characters, photographs and color documents. Higher image quality, higher definition, higher speed, and continuous output are further concurrent demands, and these demands will arguably become yet more exacting in the future.
As carrier particles that satisfy these demands, lightweight composite particles that have a specific gravity in the range of about 2.0 to 5.0 and that do not result in toner breakage even at high speeds or continuous output are widely used at present.
Demands for enhancing the characteristics of carrier particles are increasing, and in order to achieve higher image quality, particularly in full color images, toner of small particle size is required to be excellent in chargeability, as a magnetic carrier.
Specifically, it is important that the toner be imparted with a uniform charge amount, that the charge amount should not vary even after use over long periods of time, and that the charge amount should not vary with changes in the environment. Exhibiting excellent durability is a pressing demand in magnetic carriers that satisfy these characteristics.
Japanese Patent Application Publication No. 2008-181162, Japanese Patent Application Publication No. 2000-314990, Japanese Patent Application Publication No. 2000-039740, Japanese Patent Application Publication No. H5-072815 and Japanese Patent Application Publication No. 2002-091090 disclose magnetic carriers in which (1) the particle surface of magnetic core material particles is treated with an aminosilane coupling agent, and is further coated with a resin, in order to enhance durability of the magnetic carriers.